Such fastening means have been known for a long time and were described for instance in the German journal "Surf-Magazin", no. 4/90, pages 55-58. Those known structures comprise a fin receiving or take-up box which is included in the laminate of the sailboard. The fin receiving box has an opening which faces the bottom side of the sailboard and in which a fin shaft is inserted and fixed by screws. With most of the known fastening means the opening is longer than the fin shaft so that adjustment is possible in the longitudinal direction. These designs often resulted in rupture of the fin at the fin shaft or, even more inconveniently, led to the fin box breaking out of the sailboard. Faulty material or defective design were made responsible for breakage of the first kind, the main cause being identified as sharp edges in the transitory area between the shaft and the fin (see the cited "Surf-Magazin").
With most designs, the ratio is very great between the length of the fin and the length of the shaft, being for example 9:1, and as a consequence the lever arm is unfavorable for fastening purposes. With the so-called Tuttle-Box (see the cited publication) this ratio was rendered more favorable by making the shaft longer. Thereby the fin receiving box becomes higher and extends substantially throughout the thickness of the sailboard. As viewed in a side elevation view the front and back of the fin shaft (with respect to the direction of movement) are oblique in order to permit the introduction of the shaft into the box housing it.